Success of nutrition-therapy interventions in persons with type 2 diabetes: challenges and future directions.

A systematic review was conducted by the Academy of Nutrition and Dietetics to determine the evidence for the effectiveness of individualized nutrition therapy provided by a dietitian nutritionist and evidence-based (EB) nutrition-therapy interventions in adults with diabetes. This article briefly reviews the systematic process used and summarizes the effectiveness evidence and intervention recommendations. In persons with type 2 diabetes (T2D), 18 studies met study criteria for the effectiveness question. A 0.3%-2.0% decrease from baseline in glycated hemoglobin was reported at 3 months in 13 study arms, a 0.3%-1.8% decrease at 6 months in 12 study arms, a 0.3%-1.6% decrease at 12 months with ongoing support in six study arms, and a 0.6%-1.8% decrease at >12 months in four study arms. An initial series of encounters with follow-up visits and implementation of a variety of nutrition-therapy interventions, all of which reduced energy intake, were reported. Nutrition therapy also significantly decreased doses or number of glucose-lowering medications used and resulted in improvements in quality of life. Mixed effects on cardiovascular risk factors and body weight were reported. Fourteen questions were identified related to nutrition-therapy interventions. A total of 38 studies met study criteria for the nutrition-intervention questions, from which 30 conclusion statements and 19 nutrition-practice guideline recommendations for T2D were written. Three additional NPG recommendations for T2D were written based on evidence reviewed by the American Diabetes Association. The 22 nutrition-intervention recommendations for T2D are summarized. How to implement nutrition-practice guideline recommendations effectively by health care providers and individuals with T2D remains challenging. Of importance, it is recognized that identifying and integrating EB digital health-technology tools into clinical practice are major challenges for future management of diabetes, self-management education, and support.

Weight Management: Obesity to Diabetes.

IN BRIEF Evidence supports the effectiveness of nutrition therapy across the continuum of diabetes management-obesity to prediabetes to diabetes. For people who are overweight/obese or diagnosed with prediabetes, modest weight loss is important. However, the goals of nutrition therapy for type 2 diabetes are improved glycemia, lipids, and blood pressure. To achieve these goals, a reduced energy intake is essential. For some, reducing energy intake may lead to weight loss, while for others, it may maintain weight loss or prevent weight gain. Weight loss medications and metabolic surgery have been shown to be effective weight loss therapies across the continuum.

Why Weight Loss Maintenance Is Difficult.

IN BRIEF This article reviews studies related to biological mechanisms that make weight loss maintenance difficult. Approximately 50% of weight variance is reported to be determined by genetics and 50% by the environment (energy-dense foods and reduced physical activity). Body weight is tightly regulated by hormonal, metabolic, and neural factors. Hormonal adaptations (decreases in leptin, peptide YY, cholecystokinin, and insulin and increases in ghrelin, glucagon-like peptide 1, gastric inhibitory polypeptide, and pancreatic polypeptide) encourage weight gain after diet-induced weight loss and continue for at least 1 year after initial weight reduction. Weight loss also results in adaptive thermogenesis (decreased resting metabolic rate), which is also maintained long-term. Neural factors such as dopamine also signal the need to respond to an increased desire for fatty foods after weight loss.

Research Priorities for Studies Linking Intake of Low-Calorie Sweeteners and Potentially Related Health Outcomes: Research Methodology and Study Design.

Background: In a world of finite research funding, efforts to prioritize future research topics are increasingly necessary. Objective: The aim of this study was to identify and prioritize the direction of future research in the broad area of low-calorie sweetener (LCS) intake and potentially related health outcomes by using a novel method that incorporates evidence mapping in the Agency for Healthcare Research and Quality's Future Research Needs (FRN) process. Methods: A diverse expert stakeholder panel was convened and engaged to identify research gaps and prioritize future research needs. An independent research team hosted a number of interactive webinars and elicited feedback through surveys and individual interviews with the stakeholder panel, which included policymakers, lay audience members, health providers, a research funder, individuals with food industry experience, and researchers of several different specialties. Results: The stakeholder panel generated and ranked a list of 18 FRN questions across 5 broad research areas. Overall, stakeholder panel members unanimously agreed that the research questions that will have the largest public health impact are those that address outcomes related to body weight, appetite, and dietary intake. Although the LCSs included in this FRN project have all been Generally Recognized as Safe by the FDA or approved as food additives, the recurrent concerns and confusions with regard to the "safety" of LCSs by consumers underscore the importance of communicating the science to the general public. Conclusion: Our project provides evidence that engaging a diverse expert stakeholder panel is an effective method of translating gaps in nutrition research into prioritized areas of future research.

Diabetes Nutrition Therapy: Effectiveness, Macronutrients, Eating Patterns and Weight Management.

BACKGROUND: Diabetes nutrition therapy provided for individuals with diabetes must be based on research documenting effectiveness. The roles of differing macronutrient percentages, eating patterns and weight loss interventions are controversial. METHODS: A review of research related to these topics is summarized. RESULTS: Clinical trials as well as systematic reviews and Cochrane reviews report an approximately 1-2% lowering of hemoglobin A1c as well as other beneficial outcomes from nutrition therapy interventions, depending on the type and duration of diabetes and level of glycemic control. There are no ideal percentages of macronutrients or eating patterns or both that apply to all persons with diabetes. Clinical trials demonstrate the effectiveness of modest weight loss and physical activity for the prevention or delay of type 2 diabetes. However, as the disease progresses, weight loss interventions may or may not result in beneficial glycemic and other metabolic outcomes. CONCLUSIONS: To be effective, diabetes nutrition therapy must be individualized. Treatment goals, personal preferences (eg, tradition, culture, religion, health beliefs and economics) and the individual׳s ability and willingness to make lifestyle changes all must be considered when educating or counseling individuals with diabetes. A healthy eating pattern emphasizing nutrient-dense foods in appropriate portion sizes, regular physical activity and support are important. A reduced energy intake for persons with prediabetes or type 2 diabetes and matching insulin to planned carbohydrate intake for insulin users is nutrition therapy interventions shown to be effective in achieving glycemic and other metabolic outcomes.

Lifestyle weight-loss intervention outcomes in overweight and obese adults with type 2 diabetes: a systematic review and meta-analysis of randomized clinical trials.

The majority of people with type 2 diabetes are overweight or obese, and weight loss is a recommended treatment strategy. A systematic review and meta-analysis was undertaken to answer the following primary question: In overweight or obese adults with type 2 diabetes, what are the outcomes on hemoglobin A1c (HbA1c) from lifestyle weight-loss interventions resulting in weight losses greater than or less than 5% at 12 months? Secondary questions are: What are the lipid (total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglycerides) and blood pressure (systolic and diastolic) outcomes from lifestyle weight-loss interventions resulting in weight losses greater than or less than 5% at 12 months? And, what are the weight and metabolic outcomes from differing amounts of macronutrients in weight-loss interventions? Inclusion criteria included randomized clinical trial implementing weight-loss interventions in overweight or obese adults with type 2 diabetes, minimum 12-month study duration, a 70% completion rate, and an HbA1c value reported at 12 months. Eleven trials (eight compared two weight-loss interventions and three compared a weight-loss intervention group with a usual care/control group) with 6,754 participants met study criteria. At 12 months, 17 study groups (8 categories of weight-loss intervention) reported weight loss <5% of initial weight (-3.2 kg [95% CI: -5.9, -0.6]). A meta-analysis of the weight-loss interventions reported nonsignificant beneficial effects on HbA1c, lipids, or blood pressure. Two study groups reported a weight loss of ≥5%: a Mediterranean-style diet implemented in newly diagnosed adults with type 2 diabetes and an intensive lifestyle intervention implemented in the Look AHEAD (Action for Health in Diabetes) trial. Both included regular physical activity and frequent contact with health professionals and reported significant beneficial effects on HbA1c, lipids, and blood pressure. Five trials (10 study groups) compared weight-loss interventions of differing amounts of macronutrients and reported nonsignificant differences in weight loss, HbA1c, lipids, and blood pressure. The majority of lifestyle weight-loss interventions in overweight or obese adults with type 2 diabetes resulted in weight loss <5% and did not result in beneficial metabolic outcomes. A weight loss of >5% appears necessary for beneficial effects on HbA1c, lipids, and blood pressure. Achieving this level of weight loss requires intense interventions, including energy restriction, regular physical activity, and frequent contact with health professionals. Weight loss for many overweight or obese individuals with type 2 diabetes might not be a realistic primary treatment strategy for improved glycemic control. Nutrition therapy for individuals with type 2 diabetes should encourage a healthful eating pattern, a reduced energy intake, regular physical activity, education, and support as primary treatment strategies.

Evidence-based diabetes nutrition therapy recommendations are effective: the key is individualization.

Current nutrition therapy recommendations for the prevention and treatment of diabetes are based on a systematic review of evidence and answer important nutrition care questions. First, is diabetes nutrition therapy effective? Clinical trials as well as systematic and Cochrane reviews report a ~1%-2% lowering of hemoglobin A1c values as well as other beneficial outcomes from nutrition therapy interventions, depending on the type and duration of diabetes and level of glycemic control. Clinical trials also provide evidence for the effectiveness of nutrition therapy in the prevention of diabetes. Second, are weight loss interventions important and when are they beneficial? Modest weight loss is important for the prevention of type 2 diabetes and early in the disease process. However, as diabetes progresses, weight loss may or may not result in beneficial glycemic and cardiovascular outcomes. Third, are there ideal percentages of macronutrients and eating patterns that apply to all persons with diabetes? There is no ideal percentage of macronutrients and a variety of eating patterns has been shown to be effective for persons with diabetes. Treatment goals, personal preferences (eg, tradition, culture, religion, health beliefs, economics), and the individual's ability and willingness to make lifestyle changes must all be considered by clinicians and/or educators when counseling and educating individuals with diabetes. A healthy eating pattern emphasizing nutrient-dense foods in appropriate portion sizes, regular physical activity, and support are priorities for all individuals with diabetes. Reduced energy intake for persons with prediabetes or type 2 diabetes as well as matching insulin to planned carbohydrate intake are intervention to be considered. Fourth, is the question of how to implement nutrition therapy interventions in clinical practice. This requires nutrition care strategies.

Nutrition therapy recommendations for the management of adults with diabetes.

There is no standard meal plan or eating pattern that works universally for all people with diabetes. In order to be effective, nutrition therapy should be individualized for each patient/client based on his or her individual health goals; personal and cultural preferences; health literacy and numeracy; access to healthful choices; and readiness, willingness, and ability to change. Nutrition interventions should emphasize a variety of minimally processed nutrient dense foods in appropriate portion sizes as part of a healthful eating pattern and provide the individual with diabetes with practical tools for day-to-day food plan and behavior change that can be maintained over the long term.

Nutrition therapy for diabetes: effectiveness, carbohydrates and alcohol.

Studies documenting the effectiveness of medical nutrition therapy for Type 1 and Type 2 diabetes report improvements in hemoglobin A1C (A1C), as well as in other outcomes. A variety of nutrition therapy interventions are effective. Under debate is the role of carbohydrate intake on glycemic control and weight loss in individuals with Type 2 diabetes. Some studies have reported improvements in glycemic control from reducing carbohydrate intake; however, other trials have reported no significant changes in A1C with a lower carbohydrate eating pattern. Studies comparing low-carbohydrate or low-fat diets for weight loss at 12 months report similar amounts of weight loss. Evidence for the usefulness of the glycemic index concept is debatable. For the majority of people with diabetes moderate alcohol consumption with food will have minimal, if any, acute or long-term effects on glycemic control, and may have beneficial effects on insulin sensitivity and decreased risk for coronary heart disease.

The evidence for medical nutrition therapy for type 1 and type 2 diabetes in adults.

This article reviews the evidence and nutrition practice recommendations from the American Dietetic Association's nutrition practice guidelines for type 1 and type 2 diabetes in adults. The research literature was reviewed to answer nutrition practice questions and resulted in 29 recommendations. Here, we present the recommendations and provide a comprehensive and systematic review of the evidence associated with their development. Major nutrition therapy factors reviewed are carbohydrate (intake, sucrose, non-nutritive sweeteners, glycemic index, and fiber), protein intake, cardiovascular disease, and weight management. Contributing factors to nutrition therapy reviewed are physical activity and glucose monitoring. Based on individualized nutrition therapy client/patient goals and lifestyle changes the client/patient is willing and able to make, registered dietitians can select appropriate interventions based on key recommendations that include consistency in day-to-day carbohydrate intake, adjusting insulin doses to match carbohydrate intake, substitution of sucrose-containing foods, usual protein intake, cardioprotective nutrition interventions, weight management strategies, regular physical activity, and use of self-monitored blood glucose data. The evidence is strong that medical nutrition therapy provided by registered dietitians is an effective and essential therapy in the management of diabetes.

Is there a role for the glycemic index in coronary heart disease prevention or treatment?

The clinical application of the glycemic index (GI) to the prevention and treatment of chronic diseases is controversial. No evidence exists for the implementation of low-GI diets for a reduction in coronary heart disease (CHD) mortality, events, or morbidity. Observational studies report conflicting evidence on the role of low-GI diets in CHD and risk factors for CHD. Randomized clinical trials report a small reduction in total cholesterol (-6.6 mg/dL) from low-GI diets compared with high-GI diets, but no reduction in other risk factors, such as low-density lipoprotein or high-density lipoprotein cholesterol, triglycerides, fasting glucose, insulin, or body weight. Currently, the research suggests a minimal role for the implementation of low-GI diets in the prevention or treatment of CHD.

Evidence-based nutrition practice guidelines for diabetes and scope and standards of practice.

In the 1990s, the American Dietetic Association (ADA) began developing nutrition practice guidelines for registered dietitians (RDs) and evaluating how their use affected clinical outcomes. Clinical trials and outcomes research report that diabetes medical nutrition therapy, delivered using a variety of nutrition interventions and multiple encounters, is effective in improving glycemic and other metabolic outcomes. The process of developing nutrition practice guidelines has evolved into evidence-based nutrition practice guidelines, which are disease/condition-specific recommendations and toolkits. An expert work group identified important clinical questions related to diabetes nutrition therapy. Research studies were analyzed and evidence summaries and conclusion statements written and graded for strength of research design. Based on the research conclusions, evidence-based nutrition recommendations and guidelines for adults with type 1 and type 2 diabetes were formulated. The ADA evidence-based nutrition practice guidelines for diabetes are published in the Web-based evidence analysis library. The recommendations are similar to those of the American Diabetes Association, although developed using a different method. To define the RD's professional practice, the ADA has published the Scope of Dietetics Practice Framework, the Standards of Practice and Standards of Professional Performance, and specialized standards for the RD in diabetes nutrition care. The latter defines the knowledge, skills, and competencies required by RDs to provide diabetes care at the generalist, specialist, and advanced practice level.

Weight-loss outcomes: a systematic review and meta-analysis of weight-loss clinical trials with a minimum 1-year follow-up.

OBJECTIVE: To assist health professionals who counsel patients with overweight and obesity, a systematic review was undertaken to determine types of weight-loss interventions that contribute to successful outcomes and to define expected weight-loss outcomes from such interventions. DESIGN: A search was conducted for weight-loss-focused randomized clinical trials with >or=1-year follow-up. Eighty studies were identified and are included in the evidence table. OUTCOMES MEASURES: The primary outcomes were a measure of weight loss at 6, 12, 24, 36, and 48 months. Eight types of weight-loss interventions-diet alone, diet and exercise, exercise alone, meal replacements, very-low-energy diets, weight-loss medications (orlistat and sibutramine), and advice alone-were identified. By using simple pooling across studies, subjects mean amount of weight loss at each time point for each intervention was determined. STATISTICAL ANALYSES PERFORMED: Efficacy outcomes were calculated by meta-analysis and provide support for the pooled data. Hedges' gu was combined across studies to obtain an average effect size (and confidence level). RESULTS: A mean weight loss of 5 to 8.5 kg (5% to 9%) was observed during the first 6 months from interventions involving a reduced-energy diet and/or weight-loss medications with weight plateaus at approximately 6 months. In studies extending to 48 months, a mean 3 to 6 kg (3% to 6%) of weight loss was maintained with none of the groups experiencing weight regain to baseline. In contrast, advice-only and exercise-alone groups experienced minimal weight loss at any time point. CONCLUSIONS: Weight-loss interventions utilizing a reduced-energy diet and exercise are associated with moderate weight loss at 6 months. Although there is some regain of weight, weight loss can be maintained. The addition of weight-loss medications somewhat enhances weight-loss maintenance.